Class: CloudProviders::ElasticBlockStoreGroup

Inherits:
Ec2Helper show all
Defined in:
lib/cloud_providers/ec2/helpers/elastic_block_store_group.rb

Overview

ElasticBlockStoreGroup class allows easy manipulation of EBS volumes matching defined criterias. Existing volumes in cloud’s availability zones that match the criterias will be selected for the group. When cloud instances need to attach EBS volumes from the group, the attach method should called. When attaching volumes the ElasticBlockStoreGroup will select existing (unattached) volumes until there are non, afterwhich the group will create new volumes according to the criterias given as needed.

Currently, EBS volumes will not be deleted when tearing down a cloud. This is because poolparty is stateless and thus deleting drives from it will probably result in catastroph (deletions will be too general and delete stuff you don’t want deleted). Hopefully, we will come up with a scheme for a deletion flag of some sort to solve this situation.

Instance Attribute Summary

Attributes inherited from CloudProvider

#init_opts, #name

Instance Method Summary collapse

Methods inherited from Ec2Helper

#as, #ec2, #elb, #pool, property, #rds

Methods inherited from CloudProvider

#bootstrap_nodes!, #default_keypair_path, default_keypair_path, #method_missing, #run

Constructor Details

#initialize(name = cloud.proper_name, init_opts = {}, &block) ⇒ ElasticBlockStoreGroup

Returns a new instance of ElasticBlockStoreGroup.



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# File 'lib/cloud_providers/ec2/helpers/elastic_block_store_group.rb', line 14

def initialize(name=cloud.proper_name, init_opts={}, &block)
  @volumes=[]
  super
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class CloudProviders::CloudProvider

Instance Method Details

#after_initialized ⇒ Object 



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# File 'lib/cloud_providers/ec2/helpers/elastic_block_store_group.rb', line 18

def after_initialized
  unless @volumes.size > 0 
    filters={:size => size, :availabilityZone => availability_zones}
    filters[:snapshotId]=snapshot_id if snapshot_id
    @volumes=cloud.list_ec2_volumes filters
  end
end

#attach(nodes) ⇒ Object 



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# File 'lib/cloud_providers/ec2/helpers/elastic_block_store_group.rb', line 55

def attach(nodes)
  nodes.each{|node|
    # Check no volumes are attached to node on device
    skip_node=false
    cloud.list_ec2_volumes.each{|vol| 
      if vol.attached?(node.instance_id) and vol.device == device
        warn "A volume is allready attached to device #{device} of instance #{node.instance_id}" 
        skip_node = true
      end
    }
    unless skip_node
      vol=get_free_volume(node.zone)
      vol.attach(node,device) 
    end
  }
end

#create(availability_zone) ⇒ Object

Create new volume on availability_zone



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# File 'lib/cloud_providers/ec2/helpers/elastic_block_store_group.rb', line 47

def create(availability_zone)
  options={:availability_zone => availability_zone, :size => size.to_s}
  options[:snapshot_id]=snapshot_id if snapshot_id
  vol=ElasticBlockStore.new(ec2.create_volume(options),:cloud => cloud)
  @volumes<<vol
  vol
end

#free_volumes(availability_zone) ⇒ Object

get volumes that are not attached



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# File 'lib/cloud_providers/ec2/helpers/elastic_block_store_group.rb', line 34

def free_volumes(availability_zone)
  @volumes.flatten.select{|vol| vol.available? and vol.availability_zone == availability_zone}
end

#get_free_volume(availability_zone) ⇒ Object

Get a free volume from existing volumes in group or create a new one



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# File 'lib/cloud_providers/ec2/helpers/elastic_block_store_group.rb', line 38

def get_free_volume(availability_zone)
  free=free_volumes(availability_zone)
  if free.size>=1
    return free[0]
  end
  create(availability_zone)
end

#verify_attachments(nodes) ⇒ Object 



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# File 'lib/cloud_providers/ec2/helpers/elastic_block_store_group.rb', line 72

def verify_attachments(nodes)
  nodes_without_volume=nodes.select do |node|
    volumes_attached_to(node.id).size=0
  end
  attach nodes_without_volume if nodes_without_volume.any?
end

#volumes(*volume_ids) ⇒ Object 



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# File 'lib/cloud_providers/ec2/helpers/elastic_block_store_group.rb', line 25

def volumes(*volume_ids)
  return @volumes if volume_ids.size==0
  volume_ids.each{|volume_id| @volumes << cloud.list_ec2_volumes(:volumeId => volume_id)}
end

#volumes_attached_to(instanceId) ⇒ Object 



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# File 'lib/cloud_providers/ec2/helpers/elastic_block_store_group.rb', line 29

def volumes_attached_to(instanceId)
  @volumes.select {|vol| vol.attached?(instanceId)}
end